In Report and Order FCC 11-126 released last Thursday, the FCC reinstated its rules requiring insertion of audio narrated descriptions of a TV program's key visual elements into natural pauses in dialogue. This audio service is referred to as "Video Description. Not all programs require description; refer to the Report and Order for details on where it is applicable.
Broadcasters must be in full compliance with the rules by July 1, 2012. For the main ATSC service, most stations will add a second audio channel with program audio and the video description that viewers can access by selecting a different language on their cable set-top boxes. (See my March 10, 2011 RF Report article FCC Issues Video Description Reinstatement NPRM for more information.)
The situation is more complicated when A/153 mobile DTV is involved. While stations could take the same approach as on the legacy service--duplicate the entire audio stream and run it on a second channel--the bandwidth required for audio becomes significant with video bitrates of 450 kbps or less. The ATSC Mobile DTV standard allows transmitting only the video description narration on the second channel and mixing it with existing audio from the program audio channel. This saves bandwidth, but adds complexity as most network programming with video description will be distributed combined with a stereo or mono version of the program audio, making it difficult, if not impossible, for stations to separate the narration for independent transmission on the mobile DTV signal. Mobile DTV receivers will also have to be modified to include support for video description.
The NAB argued for a delay in applying video description rules to Mobile DTV, stating that the current generation of Mobile DTV devices is limited in number and that Mobile DTV receivers supporting video description will probably not be available for at least two years.
The FCC agrees with the NAB:
"Given the nascency of this service, and the fact that requiring pass-through of video description with Mobile DTV broadcasts would have little benefit to consumers at this time, we agree with NAB that it is appropriate to delay the effectiveness of these rules."
The deadline for transmitting video description on Mobile DTV has now been pushed back to Oct. 8, 2013.
Although the main reason for requiring video description is to allow people with visual impairments to enjoy TV, I can see another benefit for Mobile DTV. Drivers shouldn't watch TV while driving. This is illegal in most, if not all, states. However, with video description they may be able to safely enjoy their programs while driving with no more distraction than listening to the radio.
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